Thermal insulation for cathode



July 15, 1958 A. H. IVERSEN THERMAL INSULATION FOR CATHODE Filed April 19, 1954 INVENTOR ARTHUR HJVERSEN ATTORNE United States Patent Ofiice 2,843,785 Patented July 15, 1958 Calif., assignor to Syla corporation of Massa- This invention relates to laminar electrode tube struc" ture.

In particular it relates to cathode support structure whereby a rigid support is provided for a conventional type, rectangular in cross section, cathode sleeve and in which heat loss, due to conduction to the cathode support is minimized.

It is an object of the invention to provide for a support for a cathode which shall minimize heat conduction from the cathode to the tube proper.

It is a further object of the invention to provide for means whereby the cathode and its support may be easily assembled with respect to other electrodes of the mount.

Still another object of the invention is to provide means to allow for expansion of the cathode without affecting the spacing between the cathode and adjacent electrodes.

Other objects will appear after reading the following specification in conjunction with the accompanying drawings in which- Fig. 1 is an exploded view of a mount incorporating the novel cathode sleeve support and Fig. 2 is a perspective view of the assembled mount.

Referring to the drawings more in detail, at is dis closed the base of a wafer stem, the base being preferably of ceramic material such as alumina, zircon or steatite. Extending through the base are a number of pins 12 to some of which the electrodes of the mount are electrically connected. There are also two long pins 14 bridged by a cross bar 16 to which an assembled mount is welded.

The mount comprises a number of electrodes with suitable spacers therebetween all compacted together by means of a pair of pins 18 having enlargements in the form of circular beads 20 surrounding the pins near one end thereof. In the specific instance shown the mount is a triode comprised of paralleled anodes 22 and 24, paralleled grids 16 and 23 and a cathode of which the sleeve is shown at 30. The sleeve is a tube, rectangular in cross section and coated on the outside with emissive material. The cathode comprises the said sleeve 30 and a filament 32 inserted therein together with a pair of supporting loops 34, these loops each having aligned legs 36, one of which is elongated as at 38 for suitable securement to a pin as will be described later in detail. These loops are made of No. 4 alloy, a composition consisting of 6% chromium, 36% nickel, and 58% iron, or similar material having a low heat conductivity. These aligned portions 36 and 38 are welded to opposite sides of the cathode sleeves along faces which are not, or had not been, coated. The mount also comprises a number of insulating sleeves and washers as will be described in greater detail shortly. The anodes 22 and 24 each comprise channel members each having a web portion 40 and two flange portions 42. The center portion of the web is raised above the level of the web as indicated at 44, the raised portion having prolongations 46 extending in a direction at right angles to the longitudinal dimension of the anode.

The mount is assembled by threading the anode 22- over the pins 18' until the web portion abuts the enlargements 20. Next insulating sleeves 48 of alumina or the like are threaded over the pins, the bottoms of the sleeves resting on the upper face of the web 40. Surrounding the sleeves and resting on the web 40 are two insulating washers 50, these washers serving to support the lowermost grid 26. This grid may comprise a molybdenum frame with grid lateral wires 52 suitably secured thereto or may be a ceramic frame with suitable metalic coating on one face thereof and with the grid lateral Wires secured to the coating. The, frame is provided with an opening elongated in the direction of the raised portion 44 and with a pair of recesses 54 to snugly embrace the sleeves 48. The grid is placed on the lower washers with the grid laterial wires facing uppermost. Next threaded onto the sleeves are a second pair of insulating Washers 50 and on these Washers is laid the cathode with the loops 34 of the cathode sleeve on the washers and embracing the sleeves. These loops are loose fitting with respect to the sleeves so that they may slide on the intermediate washers 50 to allow for expansion of the cathode sleeve as the same is heated by the filament without warping of the cathode in the direction of the grids. Threaded onto the sleeves 48 and resting on the loops 34 is a third pair of insulating washers 50 and resting on these washers is the second grid 28, this grid being placed on the washers with the grid wires facing downward. As indicated in the drawing, the grid 28 is similar to the grid 26.

Threaded over the sleeves 48 and resting on the second grid 28 is a last pair of insulating washers 50 and threaded over the pins 18 and resting on these last washers is the anode 24, this anode being similar in all respects to the anode 22 but with the flanges facing in an opposite direction. After the parts have been thus. assembled on a suitable jig they are clamped together so as to make a compact mass of the assembly but yet with suflicient freedom of motion for the loops 34 so that they may slide with respect to the sleeves 48 and the adjacent washers 50. When the parts are compacted the upper ends of the pin 18 are riveted or swaged over the upper face of the web of the anode 24, thus firmly bonding all parts together. Suitable tabs 56 are attached in electro-conductive relation with the grids 26 and 28, these tabs being secured to suitable pins 12 of the stem. The extension 38 of one of the loops is suitably welded to another of the pins of the stem while the ends of the pins 18 below the circular beads 20 are welded to the crossbar 16. If desired a getter assembly comprised of a post 58 and getter frame 60 may be welded to each other and onto the top of one of the pins 18 or to one of the flange portions 42 of the upper anode 24.

Having thus described my invention what is claimed is:

1. In a mount, a cathode support comprising a pair of pins, insulating sleeves about the pins, and a pair of insulating washers on each of said sleeves, a cathode tube, rectangular in cross section, said tube being coated with emissive material on opposite exterior faces thereof, a pair of loop supports of low heat conductivity affixed to said tube in opposed relationship to one another, these supports being afiixed to the other exterior faces of the tube, the loop supports being looped over the sleeves and slidably held in between the pairs of washers.

2. In a mount, an elongated bottom anode section, a pair of insulating sleeves on each end of the anode section, each sleeve having an insulating washer threaded thereover and abutting the anode section, a grid element having recessed ends abutting the washers and partially surrounding the sleeves, a second pair of insulating washers threaded over the sleeves and abutting the grid element, a cathode tube, rectangular in cross section and provided with loop supports of poor heat conductivity, supported by said second pair of washers with the loop supports threaded over the sleeves and resting on and slidably in between the second pair of vWashers, a third pair of insulating washers threaded over the sleeves and resting on the loop supports, a second grid element having recessed ends abutting the third pair of washers and partially surrounding the sleeves, a fourth pair of insulating Washers threaded over the sleeves and abutting the second grid element and a top anode section abutting the fourth pair of washers and the tops of the sleeves, all combined with pins threading the bottom anode section, the pins being formed adjacent their ends to compactly hold the parts together.

3. In a mount, a cathode support comprising a pair of pins, insulating sleeves about the pins, and a pair of insulating washers on each of said sleeves, a cathode tube, rectangular in cross section, said tube being coated with emissive material on opposite exterior faces thereof, a pair of loop supports aflixed to saidtube in opposed relationship to one another, these supports being aflixed to the other exterior faces of the tube, the loop supports being looped over the sleeves and slidably held in between the pairs of washers.

References Cited in the file of this patent UNITED STATES PATENTS 1,828,524 Delaney Oct. 20, 1931 1,852,020 Metcalf Apr 5, 1932 2,335,818 Trumbull Nov. 30, 1943 2,378,164 Bosch June 12, 1945 2,481,061 Anderson Sept. 6, 1949 2,639,405 Benedict May 19, 1953 

